Electric switch gear



March 28, 1939. H, HILL 2,152,478

' ELECTRIC SWITCH-GEAR Filed June 5, 1936 Fig. L I

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Charles H. Hill, by Hi Attorneg.

portion of Patented Mar. 28, 1939 UNITED STATES PATENT OFFICE ELECTRICSWITCH GEAR.

Charles H. Hill, Drexel Hill, Pa.., assignor to General ElectricCompany, a corporation of New York My invention relates to electricswitchgear, more particularly to switchgear of the drawn-out typewherein a circuit breaker is bodily movable to connected anddisconnected positions with respect to stationary circuit connections.

Heretofore in electric switchgear of the aforesaid type, andspecifically the drop-down type, various methods and mechanisms havebeen employed for lifting and lowering the circuit breaker to connectedand disconnected positions, respectively, such as, for example, motoroperated gearing, manual notching or racking means, separate auxiliarytrucks, etc. In general, these devices have proved expensive,particularly for circuit breakers of moderate size, and in many casesare slow and awkward when time is an important factor.

The principal object of my invention is the provision of an improvedswitchgear unit wherein the circuit breaker can be manually lifted andlowered, respectively, to connected and disconnected positions easilyand quickly, and wherein the manual operating mechanism is simple,efficient and inexpensive.

My invention will be more fully set forth in the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaimed annexed to and forming a part of this specification.

Referring to the drawing, Fig. l is an elevational View illustrating aswitchgear unit embodying my invention in the disconnected position;Fig. 2 is a side view, partly in section, of a Fig. 1; Fig. 3 is a viewsimilar to Fig. 1 showing the switchgear unit in the connected position,and Fig. 4 is a graphical illustration of forces involved in theconnecting or lifting operation.

The switchgear unit shown by Fig. l is of the so-called drop-down metalclad type comprising a stationary supporting frame I and a circuitbreaker 2 of suitable interrupting capacity, such as an oil circuitbreaker for example, mounted for vertical reciprocal movement within theframe. In the conventional design, a sheet metal structure i forms withthe frame l an enclosing housing. Coacting with the circuit breaker 2are stationary circuit connections 3 and i which are usually connectedto busbars (not shown) mounted and supported in the upper part of thehousing 5. The connections 3 and 4 terminate in stationary disconnectcontacts (not shown) within cylindrical insulating shells 5 and 6,respectively, secured to the frame I for coaction with the movabledisconnect contacts I and 8 beneath the shells 5 and B and carried bythe circuit breaker 2 The disconnect contacts may be of any suitableform, such as of the plug and socket type for example, the contactsbeing in engagement within the lower portions of the insulating shellswhen the circuit breaker 2 is elevated as indicated in Fig. 3. Thedisconnect contacts 1 and 8 are carried at the upper ends of the circuitbreaker lead-in bushings l and 8', which extend through the breakercover 2 and are connected to the conventional oil circuit breakercontact structure within the breaker tank. These details are omitted inthe interest of clearness since the type of disconnect contacts and theinternal structure of the circuit breaker have no bearing on the presentinvention.

Suitable breaker operating means, such as a solenoid operating mechanismfor example, generally indicated at 9, is mounted on and carried by thecircuit breaker by means of a bracket l6 suitably connected to thebreaker cover 2. Where the mechanism 9 is electrically controlled,coacting disconnect contact structure at H and 12 connects the mechanismwith the secondary or control circuits when the breaker is elevated tothe connected position as shown. by Fig. 3.

For the purpose of guiding and supporting the circuit breaker 2 withinthe frame l, the frame is provided at one side thereof with a pair ofguide rods I3 secured at their upper and lower ends, respectively, tocross members l4 and I5 forming part of the frame I. The guide rods l3have slidably mounted thereon a saddle plate or carrier member 16 havingguide rings [6 on which the breaker is supported in a manner presentlydescribed, and in a preferred form of my invention the plate is normallybiased upwards against the weight of the breaker by springs l1 mountedon the guide rods 13, the weight of the breaker, however, overcoming thespring resistance as shown by Fig. 1.

From the above it will be observed that the circuit breaker 2 issupported only at one side thereof in cantilever fashion, although itshall be understood that the above described supporting and guidingarrangement can be used at opposite sides of the breaker, if desired, toequalize stresses.

Referring more specifically to the breaker supporting arrangement, theplate [6 (Fig. 2) has secured thereto at its inner side a pair of lugsl8 each having a vertical extension l8 coacting with a notched lug l9secured to the housing of the circuit breaker 2. Two or more spaced lugsl8 are provided for carrying the breaker as indicated in Fig. 1. Thebreaker is vertically positioned by means of adjustable studs 20 whichare secured to the plate l6 beneath the lugs l8 and abut the side of thecircuit breaker housing as clearly shown by Fig. 2.

Coacting with the springs I! for elevating and lowering the breaker 2 isa manual operating device comprising a toggle including a bellcrank 2|pivotally mounted at 22 on the stationary frame I, and a link 23pivotally connected at 24 to the plate l6. One arm of the bellcrank 2iis pivotally connected at the toggle knee 25 to the link 23 and theother arm 26 is formed as a socket member for receiving a bar 21, asindicated in Fig. 3, for manual operation of the toggle. When thebellcrank 2| is rotated counterclockwise, as viewed in Fig. 1, thetoggle 2 I-3 is straightened and the circuit breaker 2 raised on its.guides to its connected position as shown by Fig. 3. The raising andlowering of the circuit breaker is of course associated with suitableinterlocking means for preventing opening or closing of the disconnectcontacts on load current when the breaker is closed. Such means are wellknown in the art and may, for example, be of the char-- acter disclosedand claimed in Paxton et al. Patent No. 2,043,113, granted June 2, 1936,for Metal enclosed switchgear. Since such interlocking means forms nopart of the present invention, illustration thereof is omitted in theinterest of clearness.

In the operation of switchgear of this character, a single attendant maybe called upon to perform the connecting or disconnecting operation andit is, therefore, highly desirable that a moderate application of forcebe effective to lift the comparatively heavy circuit breaker structurethroughout its entire range of movement. That is, there should be nohigh resistance point in the operation.

To this end, the desirable characteristics of a toggle are combined withthe characteristics of a coil spring under compression so as to produceby application of a moderate manual effort a uniformly high operatingforce throughout the entire range of operation. In other words, when themechanical advantage of the toggle is at its lowest value, as shown inFig. 1, the. compression springs I1 exert their maximum upward force. Asthe spring force decreases during the upward travel, the mechanicaladvantage of the toggle increases until it reaches its maximum justprior to its straightened position near the upward limit of travel.

It will, therefore, be noted that the springs and the toggle cooperatein the most effective man-- her to provide a smooth and uniformoperating force. Knowing these factors, it is a comparatively simplematter to design the toggle and springs so that the switchgear can beeasily operated by a single attendant.

This point can be more clearly brought out by reference to Fig. 4illustrating graphically forces involved in lifting the breaker fromdisconnected to connected position. The force-distance curve aillustrates the manual effort which would be required to lift thebreaker by the toggle alone. It will be noted that a high initial effortis required. Curve b represents the manual effort required to lift thebreaker by the combined arrangement of toggle and spring. No highresistance point appears and near the end of the connecting operationwhere the resistance is nor mally high, due to engagement of thedisconnect contacts, etc., the power available is greatly in excess ofthat required.

The circuit breaker 2 can be held in its upper connected position by thetoggle when in an overset position, as illustrated by Fig. 3, the togglebeing restrained in said overset position by an adjustable stop member28 secured to the plate l6. If desired, a latch 25a pivotally mounted onthe frame I and biased toward. latching position by a spring 252) can beprovided for holding the toggle in such position as a precaution againstaccidental lowering of the breaker. This latch, of course, would bereleased such as by lifting of a trip rod 9a when the breaker is trippedmanually at the trip lever 92) which is also adapted to trip the breakermechanism (not shown) in the connected position shown by Fig. 1preparatory to lowering. The lowering or disconnecting operation isperformed simply by rotating the operating bar 21 clockwise.

Although, in the construction shown by Fig. l, the weight of the breaker2 entirely overcomes the resistance of the springs I! in. thedisconnected position, it is apparent that the springs may be inaddition compressed somewhat by the manually operated linkage. A simplelatch, such as shown at 30, for the linkage would then. be used asindicated in Fig. 1 to hold the springs compressed. The latch 30 can bepivotally supported on the frame I by a lug 3| for engaging the carrierguide ring 16'. A stop 32 secured to the frame coacts with the latch asshown. This arrangement would give an initial impulse or acceleration tothe breaker when. the latch is released by the trip 9a, preceded ofcourse by slightly depressing the carrier to provide clearance for thelatch prior to the beginning of the lifting operation. Where such alatch is used, the carrier member 16 can also be held in its lowerposition against the bias of the springs when the breaker is removed forinspection or replacement.

It should be understood that my invention is not limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the artwithout departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. Electric switchgear of the draw-out type comprising a stationarysupporting frame, a circuit breaker adapted to be tripped by manualmeans bodily movable in a vertical direction in said frame to connectedand disconnected positions, a linkage forming a toggle including amanually operated bell crank pivotally supported on said frame and alink interconnecting said bell crank and said breaker, said toggle beingcollapsed in the lowered position of said breaker, a latch mounted onsaid frame for engaging said toggle and holding the same in extendedposition when said breaker is raised to connected position, and meansfor releasing said latch when said breaker is tripped. by said manualmeans.

2. Electric switchgear of the draw-out type comprising a stationarysupporting frame, a circuit breaker bodily movable in a verticaldirection in said frame to connected and disconnected positions, meansfor raising and lowering said circuit breaker between said positionsincluding a toggle linkage and spring structure each operativelyinterconnecting said frame and breaker arranged so that in the loweredposition of the breaker the spring structure is under maximum tensionand the mechanical advantage of said linkage is a minimum, a latchcoacting with said frame and breaker for holding said spring structureunder compression in said iowered position, and means independent ofsaid spring for applying an operating force to said linkage for raisingsaid circuit breaker upon. reiease of said latch.

3. Electric switchgear of the draw-out type comprising a stationarysupportin frame, a circuit breaker adapted to be tripped by manual meansbodily movable in a vertical direction in said frame to connected anddisconnected positions, a manually operated toggle linkage operativelyinterconnecting said frame and breaker, a latch pivoted on said frameand coacting with the knee of said toggle linkage for preventingaccidental collapse of said toggle, and means for releasing said latchupon tripping of said breaker by said manual means, and spring structurenormally biasing said breaker in the upward direction, the resistance ofsaid spring structure being substantially overcome by the Weight of saidbreaker when said breaker is in its lowered disconnected position.

4. Electric switchgear of the draw-out typecomprising a stationarysupporting frame, a circuit breaker adapted to be tripped by manualmeans bodily movable in a vertical direction in said frame to connectedand disconnected positions, a pair of vertical guide rods secured to oneside of said frame, a carrier member secured to and slidable on saidrods, said breaker and carrier member having coacting supporting lugs bywhich said breaker is hung in detachable relation on said carrier memberalong the inner side thereof, means including a manually operatedlinkage interconnecting said frame carrier member for raising andlowering said breaker, a latch coacting with said frame and linkage forholding said linkage in extended position for precluding accidentallowering of said breaker, and means for releasing said latch upontripping of said breaker by said manual means.

5. Electric switchgear oi the draw-out type comprising a stationarysupporting frame, a circuit breaker bodily movable in a verticaldirection in said frame to connected and disconnected positions,vertical guide rods secured to one side of said frame, a verticallypositioned carrier so cured to and slidable on said rods, said breakerand carrier having coacting supporting lugs by which said breaker ishung in detachable cantilever relation on said carrier along the innerside thereof, an adjustable member mounted on said carrier beneath saidlugs adapted to abut said breaker for adjusting the position of thevertical axis thereof, and means for raising and lowering said carrier.

CHARLES H. HILL.

